This study presents a new approach to formulating cellulose acetate (CA), polylactic acid (PLA), and polyhydroxybutyrate-co-valerate (PHBV) biobased blends, with a focus on their dielectric and rheological performances for an electrical insulation application. FTIR and rheological analysis showed a molecular interaction in PHBV:CA and PLA:CA blends between the carbonyl groups of PLA and PHBV, and the hydroxyl groups of CA. Dielectric study showed that temperature, frequency, and polymer nature are key parameters influencing the blends' dielectric constant (ε′) and loss factor (ε'') for room and high temperatures. Even though CA-based blends possessed the highest dielectric constants at room temperature, they showed the lowest thermal-sensitive behavior. The measured dielectric properties showed potential applications of PLA-based blends for low-temperature electrical insulation and CA-based blends for high-temperature electrical insulation.